Beth R. Loveys

Transfer of photosynthate and naturally occurring insecticidal compounds from host plants to the root hemiparasite Santalum acuminatum (Santalaceae)

Plant hemiparasites obtain a wide range of primary compounds from their host plants, including carbon, water and ions. In this paper, we examine the transfer of carbon from the host plant Myoporum parvifolium and the movement of an insecticidal compound from the host Melia azedarach to the root hemiparasite Santalum acuminatum(R.Br) (quandong). By using 14 C we determined that glucose was moving from the M. parvifolium host to the parasite while the carbon fixed by quandongs was found to be mostly in mannitol. Mannitol occurred in fruit, leaf, stem and root tissue and also in xylem sap. We also provide evidence from direct infusion electrospray mass spectrometry (DIEMS) that quandong fruit from trees growing near Melia azedarach (L.) contain an insecticidal compound. This was supported by results from a bioassay in which apple moth (Epiphyas postvittana Wal ker) larvae suffered higher mortality when fed only on quandong fruit that was growing nearM. azedarach than those fed on quandong fruit from trees growing away from M. azedarach.

Water relations and gas exchange of the root hemiparasite Santalum acuminatum (quandong)

The water relations and leaf gas-exchange characteristics of the root hemiparasite quandong (Santalum acuminatum (R.Br.) A.DC) and its neighbouring plants were examined at three field sites in central Southern Australia. This paper examines the role of water potential and osmotic gradients in facilitating the movement of water from host plants to quandong. Quandong exhibited a significantly more negative water potential than the neighbouring plant species at both field sites during summer and winter. A significant proportion of the osmotic potential was accounted for by mannitol, Na + , K + and Cl - . A water potential difference of 1.7 MPa was maintained between quandong and its putative host over a measurement period of 24 h. Xylem sap and leaves of quandong contained considerable concentration (0.1–0.4 mol (kg tissue water) –1 ) of mannitol. Stomatal conductance and assimilation of quandong were lower than those of the neighbouring plants at both Middleback and Aldinga during both summer and winter measurements. Measurements of transpiration for quandong differed between the two sites. The lower transpirational water loss resulted in quandong at Middleback having an instantaneous water-use efficiency higher (0.13–2.2 µmol (CO 2 ) mmol –1 (H 2 O)) than the neighbouring plants. Daily sap flow and calculated hydraulic conductivity were not significantly different between quandong and putative host plant.

Effect of different host plants on the growth of the root hemiparasite Santalum acuminatum (quandong)

In recent years, the root hemiparasite Santalum acuminatum (quandong) has become an increasingly important commercial crop within the indigenous foods market. Relatively little is known of the significance of the host species on quandong growth and development. This paper presents data from a glasshouse pot experiment showing the effect of 4 different host species on the growth of quandong. Quandong growth, as measured by height and dry-mass accumulation, was significantly improved when grown in the presence of a host plant compared with being grown alone. Quandong grown with a host achieved an average height of 45 cm, while those grown alone grew up to only 37 cm. The host species also had an impact on the growth of quandong. Quandong had no detrimental effect on the growth of its host plant. Quandong grown with Myoporum parvifolium and Atriplex nummularia accumulated a significantly greater amount of dry biomass than quandong grown alone.

Disturbance is required for CO2-dependent promotion of woody plant growth in grasslands

The relative effects of disturbance (here defined as bare soil), competition for edaphic resources, thermal interference and elevated [CO2] on growth of tree seedlings in grasslands were studied under field conditions. Snow gum (Eucalyptus pauciflora Sieb. ex Spreng.) seedlings were grown in open-top chambers flushed with either ambient or elevated [CO2] from March 2004 to January 2005 (autumn to summer). These seedlings were planted into three treatments (i.e. bare soil, soil covered with straw or soil supporting a sward of live pasture grass) to separate effects of grass on seedling growth into those due to competition with grass for soil resources or to alteration of the thermal environment caused by a grassy surface (Ball et al. 2002). After the first major autumn frost, seedlings growing in competition with grass lost 59% of their canopy area, whereas those growing in bare soil or straw suffered negligible damage. These results reveal the complexity of competitive inhibition of plant growth in which ineffective competition for resources such as soil water enhances the vulnerability of the plant to abiotic stress, in this case frost. Tree seedlings growing in bare soil and straw commenced growth earlier in spring than those growing in competition with grass, where soil moisture was consistently lowest. Under ambient [CO2], growth was greater in bare soil than in straw, consistent with thermal interference, but these differences disappeared under elevated [CO2]. Elevated [CO2] significantly increased biomass accumulation for seedlings growing in bare soil and straw treatments, but not in grass. Thus, elevated [CO2] alleviated apparent thermal interference of seedling growth in spring but did not overcome adverse effects on seedling growth of either competitive reduction in soil resources or competitive enhancement of environmental stress. Nevertheless, elevated [CO2] could promote invasion of grasslands due to enhancement of woody plant growth in bare soil created by disturbances.

Flipping the laboratory: improving student engagement and learning outcomes in second year science courses

ABSTRACT The flipped classroom pedagogy was implemented in two core undergraduate science courses; Animal and Plant Biochemistry II (APB) and Microbiology and Invertebrate Biology II (MIB) to encourage students to prepare for laboratory classes. Students often attend class without little understanding or appreciation of what they are going to learn in the laboratory, the types of techniques they are going to use or the safety precautions required. This is not only hazardous for students but also requires detailed explanations from teaching staff at the start of class, overloading students with information. This disconnection between theory and practice was overcome by ‘flipping the laboratory’ to integrate online, interactive pre-laboratory activities into the curriculum. The aims of this study were to: (1) evaluate student engagement with pre-laboratory content; (2) investigate student performance and learning outcomes; (3) review failure rates following implementation of pre-laboratory activities. Students agreed that the pre-laboratory activities bridged the gap between theory and practice (65%) and enhanced their engagement with course material (79%). The integration of pre-laboratory activities significantly increased student learning outcomes immediately after implementation into the curriculum, despite a 26.8% increase in enrolments from 2011 to 2017. Failure rates significantly decreased in both APB and MIB over three consecutive years.